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TROS. MORISON, OF YEY YORK, N., Y.. ASSIGNOR TO A. S. SOLOMONS, OF SAME PLACE.

CHRONODIETER-ESCAPEMENT.

Specification of Letters Patent No. 21,865, dated October 19, 1858.

To all whom it may concern.

Be it known that I, Trioinis MonisoN, of the city of New York, in the State of New York, have invented a new and useful Improvementin Chronometer -Escapementsg and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawing, through letters of reference marked thereon, forming part of this specification, in which- Figure l, represents an elevation of my chronometer escapement. Fig. 2, is an inverted plan of the same, the interior of the cylinder being shown in dotted lines.

The same letters of reference, in both figures, indicate the same parts.

My invention relates more particularly to that class of chronometers which measure time by units, c'. e. a single beat to each vibration of the balance wheel, and to which class alone, the term chronometer, in its common acceptation, is now understood to apply; in which as at present constructed the detent is moved in one direction mechanically against the resistance of a spring, and is caused to resume its normal position by the reaction of said sprinO; the objections to which are- First. That considerable force is required to overcome the power of the spring carrying the detent-pallet, in disengaging it from the tooth of the escapement wheel; to effect this force, it is necessary to use a heavy balance wheel, to overcome the resistance.

Second. That the power of the detent spring is liable toV be varied considerably, by the slightest change in its position, or by a slight bend or set being given it by a sudden jerk or concussion, which must necessarily impair its operation, or, supposing that no positive injury were done to the spring-detent, by such concussion, it almost invariably checks the vibration of the balance wheel to such an extent as to render its impulse insufcient to disengage the detent against the resistance of the spring; its action consequently ceases; this is extremely liable to be the case with pocket chronometers, from the fact of their being liable to so many sudden motions of the body.

rIhird. That the spring detent and feather spring are necessarily of such extremely delicate proportions and exquisite finish, as to render them too expensive ever to come into common-use.

All these objections are overcome in my escapement, in the following' manner: First. The detent lever is perfectly balanced, and is moved back and forth mechanically so as to be (as nearly as possible) free from all friction, and unimpeded by the resistance of the detent spring. Second. There being no spring the resistance of which is to be overcome, the heavy balance wheel is unnecessary, and the friction, wear and risk of breakage of its pivots is materially reduced. Third. All the expensive parts of the common chronometer escapement are superseded by `others of simpler construction and greater durability, and at a cost scarcely exceeding if equal to that of the escapement of the well known lever watch.

To enable others to make and use my invention, I will now describe its construction and operation, and as it is applicable to every variety of watch, it is deemed superfluous to give any description of the plates, spring, train of wheels, or other parts, common to all watches, and well known.

(a.) represents the balance wheel, and (o) the hair spring on an axle (c), which supported in brackets (d, above and below the upper plate (c), in the usual manner; on this axle is a hollow cylinder with a collar or enlarged cylinder f) at each end; one side of the cylinder is open to an extent of about one sixth of its circumference more or less; within said cylinder is a pawl (n) on a. pivot, the extreme end of which protrudes a short distance through the aperture in the peripl'ieryof the cylinder, and is held to one side thereof, in the position shown in the drawing, by a semi-circular hair spring hooked onto its rear end, and keyed fast to a stud (s) in the opposite side of the cylinder; (g) is the common escapement wheel, (m) is the detent lever, with a detent pallet (u) attached to one side of it, and a curved lateral arm (o) to the other side near its end; all of which are so arranged vertically as that the end of the lever (m) nearly touches the cylinder The arm (o) is on a plane with the upper collar and the detent (u) and escapement wheel (g) are on a plane with the lower collar (if) at the back of the lever tm) near its outer end is a stud (il.) which prevents it from vibrating to that side, while the end of the arm coming in contact with the periphery of the roller prevents its vibration in the other direction,

until, by the oscillation of the cylinder (f), the pawl (n) is brought in contact with the end of the lever (m), at which time a notch in the periphery of the collar comes under the curved end of the arm which allows it to vibrate, by the force of the pawl (n) against it, sufficient-ly to allow their points to pass each other, at which moment the end of the arm (fu) rides the inclined side of the notch, into which it was depressed, onto the periphery of the collar as before; this motion liberates the tooth of the escapement wheel from the detent when the second tooth from it is suddenly brought by the impulse of the main spring against the impulse pallet (o) inthe lower collar (2), which gives impulse to the balance wheel, to be brought back by the hair spring (ZJ) at the moment the tooth of the escapeinent wheel has passed the pallet (0), another tooth is caught by the detent, to be held until a repetition of the same motion of the cylinder liberates it kas before described; in the return motion of the balance wheel the pawl comes in contact with the back of the lever (m), and having no support, is depressed within the periphery of the cylinder (f) to allow it to pass, and is thrown out again by the spring into its original position, to perform a repetition of its functions as before described.

Having thus described my invention whatV THOMAS MORISON. Vitnessesz WM. M. SMITH, DANL. SEIDAS. 

